My experience with flexible water
containers is that they are not robust enough, for boats especially if you are in the tropics, or hard on gear
as I am. Storeage becomes an issue as you have to be careful where and what you place them with, especially in rough weather
when things like to move at an alarming rate . I use 20ltr plastic military jerry cans or similar. They can take a beating, stack gear
on top or around, leave in the sun with no fear of splitting, use for solar
warm water, can also use for emergency steering
should you lose your primary means, float and can be stored anywhere on the boat. Forget flexible as one day you will have a very wet boat inside and no drinking water
. My opinion only.